Corner sander



Dec. 15, 1964 F. T DANUSKI, JR

CORNER SANDER Filed June 11, 1965 R m m V W.

FRANK 7. DANUSK/ JR.

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H/S ATTORNEYS United States Patent 3,160,995 CGR'NER SANGER Frank T. Danuslri, in, 424 lropiar Sh, Warren, Pa. Fiied June 11, 1963, fier. No. 287,6tl4 it) Elaims. (Ci. Si -17h) This invention relates to abrasion finishing apparatus such as sanders or polishers for performing certain specific finishing tasks such as smoothing edges adjacent internal walls and especially smoothing internal walled corner areas of rooms, stairs, drawers, etc. 7

Powered apparatus for sanding or polishing surfaces such as hardwood floors commonly takes the form of large disc abrasion pads that can efficiently sand-smooth the major area of the floor surface. Sanders are also available which have rectangular abrasion pads that move either in a rectilinear or in a small circular or planetary path.

While each of these types of sanders can satisfactorily perform large area finishing, none have proven to be completely satisfactory in finishing wall-edge portions and particularly corner edge portions of floors and other geometrically similar objects. One serious drawback to all existing forms of sanding apparatus, lies in their inability to conveniently abrade a surface adjacent a vertical Wall without damage to the vertical wall. Of course, disc sanders, which are most commonly used for finishing floors and other large surfaces, cannot even begin to ap proach a corner area surface.

Accordingly, it has been an object of my invention to fully investigate the theoretical and economical problems encountered in the finishing of surface areas adjacent vertical walls and especially adjacent vertical wall corners;

Another object of my invention has been to provide abrasion apparatus that can be economically and eficiently employed in the finishing of surfaces adjacent vertical walls and vertical wall corners;

Another important object of my invention has been to provide sanding apparatus for finishing edge and corner surfaces which can be powered by existing available power sources such as portable electric drills;

A further object of my invention has been to provide sanding apparatus that can finish areas closely adjacent to vertical walls and vertical wall corners without in any way damaging or marring the adjacent portions of the vertical walls.

These and other objects of my invention will appear to those skilled in the art upon reading and understanding the following disclosure of the inventive concepts upon which my invention is based, a description of a specific illustrative embodiment thereof, and the appended claims.

One phase of my invention relates to the use of an oscillating or reciprocating sector-shaped abrasion pad that has a pair of radiant side edges which move through a total angle just slightly less than the angle of a corner to be finished. Thus the sanding stroke of my apparatus is particularly adapted to the area to be finished, and the skill and time-consuming multiple operations now necessary to smooth corner areas by hand or ordinary powered equipment are effectively reduced or eliminated.

Another phase of my invention relates to the use of a sector-shaped base plate that substantially covers the entire area to be finished and extends slightly beyond the maximum limit of abrading pad travel to assure that the abrading pad does not come into contact with the adjacent portions of a vertical wall.

These phases of my invention are exemplified and more fully explained in the following description of a preferred specific embodiment of my invention wherein reference is made to the accompanying drawings, of which:

3,lfi,95 Patented ec. 15, 1%64 FIGURE 1 is an exploded perspective view of an embodiment of my invention that is constructed particularly for finishing corner portions of floors and other objects having adjacent perpendicular walls;

FEGURE 2 is a top or plan view of the device shown in FIGURE 1 in its assembled form;

FIGURE 3 is a cross-sectional elevation view taken along lines Ill-III of FIGURE 2; and

FIGURE 4 is a reduced scale operational view of the device shown in FIGURES 1 through 3, in position to finish a corner surface area. a 1

Referring now more specifically to the drawings, the illustrative embodiment of my sanding device is shown as including a sector-shaped output member, platen or abrading pad it). The abrading pad lit) has a pair of radiant side edges 11 and an arc-shaped outer peripheral edge 12 that is a segment of a circle having a center located adjacent the vertex of the sector angle A defined by the radiant side edges 11. The pad lil is provided with a pivot anchor or threaded bore 13 that is concentric with the arc-shaped edge 12. An elongated driving slot or cam surface 14 is located centrally of the pad 10 and receives a driving member as hereinafter described. Abrading material such as sandpaper or polishing cloth P is cut to approximately the same size and shape as the abrading pad it) and is provided with a suitable adhesive backing for mounting it thereon. If desired, clamp means (not shown) can be provided on the radiant edges 11 of the abrading pad lit for holding tab portions of the abrading material P in accordance with well-known practice.

A sector-shaped base plate, locating member or protective shield 15 is positioned immediately above the abrading pad 10 and supports the abrading pad It adjacent the vertex of its sector angle A and also adjacent the peripheral arc-shaped edge 12 as hereinafter de scribed. The base plate 15 has a pair of radiant side edges 16 and 17 and an arc-shaped outer peripheral edge 18 which together substantially define the perimetrical boundaries of the surface area to be finished. In most cases the radiant side edges will define a sector angle B of to correspond to the conventional 90 corners employed in conventional buildings. The arc-shaped peripheral edge 18 is a circular segment having a center located adjacent the vertex of the sector angle B.

The base plate 15 is provided with a braze-connected bearing portion containing a smooth walled bore 19 that is concentric with the arc-shaped edge 18 for pivotally connecting the abrading pad iii to the base plate 15 adjacent their respective sector vertices. A pivot pin or shaft is provided by a screw or bolt 20 that fits through the bore 19 and screws securely into the threaded bore 13. A spacing bearing member or washer 21 is positioned between the abrading pad and base plate to reduce frictional contact therebetween.

The abrading pad it) is also supportably connected to the arc-shaped peripheral edge 18 of the base plate 15 by a curved sheet metal guide or track member 22 and suitable followers 23. The track member 22 is securely mounted as by screws or other fasteners 24 to the arcshaped peripheral edge 18 of the base plate 15 as more clearly shown in FIGURES 2 and 3. The followers 23, which may be rivets or machine screws, are firmly anchored in the arc-shaped edge 12 of the abrading pad 10. The followers 23 vertically engage adjacent slot portions 22a of the track member 22, such that no bending load is imposed on the pivot pin bolt 20.

The preferred power source for any heavy duty equipment is a rotating motor and, accordingly, it is preferred to provide means for converting rotative motion into the U however, that other sources of power, such as vibrating motors can be employed without departing from the broadest scope of my invention. For converting rotative motion into reciprocating motion, I provide a crankshaft or offset drive member 25 having a crank pin or cam follower 26 that drivingly engages the cam surface 14 in the abrading pad to move the abrading pad back and forth as the crankshaft 25 is rotated.

The crankshaft 25 is operatively supported by a bearing housing 27 that is mounted securely on the base plate by a plurality of bolts 28. It will be apparent that the base plate 15, the bearing housing 27 and the track member 22 could, if desired, be die cast as a single integral unit. However, for ease of explanation, I have shown them as being completely separate. A brass bushing or bearing member 29 is pressed-secured in the bearing housing 27 and rotatably supports the crankshaft in a normally vertical orientation. The crankshaft 25 is resiliently held or biased toward the abrading plate 10 by a coil compression spring 30 that is positioned between a thrust washer 30a that engages the bearing housing 27, and the lower end or head of the crankshaft 25. A bearing plate 31 is carried by the crank pin 26 and engages edge portions of the cam surface 14 to reduce wear caused by the repeated rubbing movements during operation.

Referring now specifically to FIGURE 2 which shows the relative positions of the assembled sanding apparatus, it will be seen that the abrading pad 10 and the base plate 15 are sectors of identical circles. The maximum limits of the motion or stroke of the abrading pad 19 are represented by the broken lines 11'. It clearly appears in FIGURE 2 that the sector angle A of the abrading pad 10 is less than the sector angle B of the base plate 15 by an amount that is equal to the angular stroke of the abrading pad plus a small amount of clearance C (about & on each side) that prevents the abrading pad from ever moving outside of the boundaries defined by the radiant side edges 16 and 17 of the base plate.

The illustrative embodiment is operated as follows: The crankshaft 25 is connected to a power motive means, such as an electric drill, or in the alternative, a motor is mounted securely onto the bearing support 2'7 as a permanent part of the mechanism. When it is desired to sand a corner area or an area adjacent any vertical wall, the radiant side edges 16 and 17 of the base plate 5 are moved into contact with the adjacent side wall or walls W as shown in FIGURE 4. The motor is then operated to rotate the crankshaft 25 thus causing a rapid oscillation or reciprocation of the abrading pad it) and the abrasive paper P atfixed thereto. If desired, the entire device may be moved back and forth along the side edges 16 and 17 slightly to make the best use of the abrasive paper. However, since the movement of the abrading pad covers substantially the entire area to be sanded, there is no need to take several approaches in order to complete the sanding of any one corner. Furthermore, because of the protective feature of the base plate, there is no danger that the wall may be damaged. From the foregoing, those skilled in the art will recognize that l have provided abrading finishing apparatus that is particularly useful in sanding or polishing surface areas adjacent wall edges and especially adjacent wall corners.

While a preferred embodiment of my invention has been shown herein for purposes of illustration, it is understood that various changes may be made in this construction by those skilled in the art without departing from the spirit and disclosed concepts of the invention as particularly pointed out and defined in the appended claims.

I claim:

1. Apparatus for finishing corners comprising a base plate having a pair of radiant side edges that form an angle of substantially 90 therebetween and having a third edge in the form of a circular arc swung about a center-located adjacent a vertex of said angle, an abrading pad having a pair of radiant side edges that define an angle substantially less than 90 therebetween, and a third edge in the form of an arc swung about a center located adjacent the vertex of the angle formed by said radiant side edges, means pivotally connecting said abrading pad to said base plate at the center of said arc, and means for oscillating said abrading pad about said pivotal connection and between the radiant side edges of said base plate.

2. Apparatus as defined in claim 1 wherein the arc edge of said base plate carries a track member that extends downwardly and around the arc edge of said abrading pad, and track follower means is connected to said abrading pad and engages said track member to supportably connect said abrading pad to the base plate.

3. Abrading apparatus for finishing corner surfaces comprising, a base plate having a pair of radiant side edges that form an angle therebetween, an abrading pad having a pair of radiant side edges that define an angle therebetween which is substantially less than the angle of the corner to be finished, means operatively connecting said abrading pad to said base plate for oscillatory movement of said abrading pad within the confines of the boundary defined by the radiant side edges of said base plate and means for oscillating said abrading pad.

4. Abrading apparatus for finishing corner surfaces comprising, a base plate having a pair of radiant side edges that form an angle therebetween substantially equal to the angle of the corner to be finished, an abrading pad having a pair of radiant side edges that define an angle therebetween which is substantially less than the angle of the corner to be finished, means operatively connecting said abrading pad to said base plate for oscillatory movement of said abrading pad within the confines of the boundary defined by the radiant side edges of said base plate and means for oscillating said abrading pad.

5. Abrading apparatus for smoothing corner surfaces comprising: a sector-shaped base plate, a sector-shaped platen for removably supporting a sheet of abrasive material on one surface thereof and having a sector angle that is substantially less than the sector angle of said base plate, means pivotally connecting said platen to said base plate adjacent their respective sector vertices and means for reciprocatingly rotating said platen about said pivotal connection.

6. Abrading apparatus for smoothing corner surfaces comprising: a sector-shaped base plate having a sector angle that is substantially equal to the angle to be finished, a sector-shaped platen for removably supporting a sheet of abrasive material on one surface thereof and having a sector angle that is substantially less than the sector angle of said base plate, means pivotally connecting said platen to said base plate adjacent their respective sector vertices and means for reciprocatingly rotating said platen about said pivotal connection.

7. Abrading apparatus for finishing corner surfaces comprising: a sector-shaped base plate having a sector angle, a sector-shaped platen having a sector angle of substantially less than the sector angle of said base plate for removably supporting a sheet of abrasive material on one surface thereof, said platen having an elongated radially directed slot portion formed in a central portion thereof, means for pivotally connecting said platen to said base plate adjacent their respective sector vertices, a crank shaft extending through said base plate and including an offset crank pin that is constructed and arranged to operatively engage said slot portion and thereby move said platen through an angle that is slightly less than the sector angle of said base plate upon rotation of said crank shaft, and means securely mounted on said base plate for supporting said crank shaft.

8. Abrading apparatus for finishing corner surfaces comprising: a sector-shaped base plate having a substantially 90 sector angle, a sector-shaped platen having a sector angle of substantially less than 90 for removably supporting a sheet of abrasive material on one surface thereof, said platen having an elongated radially directed slot portion formed in a central portion thereof, means for pivotally connecting said platen to said base plate adjacent their respective sector vcntices, a crank shaft extending through said base plate and including an offset crank pin that is constructed and arranged to operatively engage said slot portion and thereby move said platen through an angle of slightly less than 90- upon rotation of said crank shaft, and means securely mounted on said base plate for supporting said crank shaft.

9. Abrading apparatus as defined in claim 8 further including additional means for supportingly connecting said platen to said base plate.

10. Abrading apparatus as defined in claim 9 further including resilient means for urging said offset crank pin into constant engagement with said slot portion.

References Cited in the file of this patent UNITED STATES PATENTS 

5. ABRADING APPARATUS FOR SMOOTHING CORNER SURFACES COMPRISING: A SECTOR-SHAPED BASE PLATE, A SECTOR-SHAPED PLATEN FOR REMOVABLY SUPPORTING A SHEET OF ABRASIVE MATERIAL ON ONE SURFACE THEREOF AND HAVING A SECTOR ANGLE THAT IS SUBSTANTIALLY LESS THAN THE SECTOR ANGLE OF SAID BASE PLATE, MEANS PIVOTALLY CONNECTING SAID PLATEN TO SAID BASE PLATE ADJACENT THEIR RESPECTIVE SECTOR VERTICES AND MEANS FOR RECIPROCATINGLY ROTATING SAID PLATEN ABOUT SAID PIVOTAL CONNECTION. 